Dual Disk SATA

  • Thread starter Thread starter Spin
  • Start date Start date
S

Spin

Gurus,

On a machine with two SATA drives, is there any performance gain by running
applications off of the second SATA disk? I understand that SATA is serial
in-line technology, that being said, if all the reads and writes have to
come through the same controller, then perhaps running applications off of
the second SATA disk might actually result in a DECREASE in total system
performance?
 
There are a number of hw items to be taken into consideration if seeking
performance, not just the drives
 
Gurus,

On a machine with two SATA drives, is there any performance gain by running
applications off of the second SATA disk?  I understand that SATA is serial
in-line technology, that being said, if all the reads and writes have to
come through the same controller, then perhaps running applications off of
the second SATA disk might actually result in a DECREASE in total system
performance?
Click to expand...

You need to understand the way SATA drives are handled. Each drive is
directly connected to a SATA port on the motherboard. They do not
connect in a Master/Slave set up on the same cable.
 
Spin said:
Gurus,

On a machine with two SATA drives, is there any performance gain by
running
applications off of the second SATA disk? I understand that SATA is
serial in-line technology, that being said, if all the reads and writes
have to come through the same controller, then perhaps running
applications off of the second SATA disk might actually result in a
DECREASE in total system performance?
Click to expand...
SATA interface speed is 1.5 or 3 GB/sec, harddrives deliver 50-70MB/sec. The
drive will be the bottleneck, and two drives (in particular with the swap
partition and personal files on the 2nd one, or even raid0/stripe) can
enhance performance somehow. There is no sense in creating a separate
partition for the swapfile on the first drive, since that would force
excessive head movements across partitions.
 
Spin said:
Gurus,

On a machine with two SATA drives, is there any performance gain by
running applications off of the second SATA disk? I understand that
SATA is serial in-line technology, that being said, if all the reads
and writes have to come through the same controller, then perhaps
running applications off of the second SATA disk might actually
result in a DECREASE in total system performance?
Click to expand...

Any inefficiencies or conflicts within the controller are insignificant and
ridiculously small compared to disk access time.

There's one technique, for example, that loads a program in disk-location
order then sorts the various pieces out in RAM.

MUCH faster than flopping all over the drive to load the pieces in logical
order to begin with.
 
If you want performance, raid/0 (Stripe) is the answer.
Click to expand...


It produces very little additional performance, but greatly increases
the risk to your data, since if any drive in a stripe is lost, all the
data on the stripe is lost.

I recommend against it.
 
Spin said:
Gurus,

On a machine with two SATA drives, is there any performance gain by
running applications off of the second SATA disk? I understand that SATA
is serial in-line technology, that being said, if all the reads and writes
have to come through the same controller, then perhaps running
applications off of the second SATA disk might actually result in a
DECREASE in total system performance?
Click to expand...

Can safely say that when I image my XP partition, and save that image to a
partition on same hard drive it is relatively slow. Slower by about a 1/3
more time as opposed to when I save the image file to another hard drive.
Both, are identical SATAs.
 
Why did my hard disk performance double? Sorry Ken but you are wrong on the
performance issue. And like I said if data is backed up properly why worry?
There is a much higher risk of losing data to a Windows failure than a hard
drive failure. Yes a stripe setup does increase the risk but the trade off
in performance increase is most definitely worth it. The only way I might
not do it is in a business environment.

Ramone
 
Why did my hard disk performance double? Sorry Ken but you are wrong on the
performance issue.
Click to expand...


That's your opinion. I disagree. I've tried RAID0 here and I saw no
discernable performance improvement at all. I know many others who
report the same thing.

I don't know why your "hard disk performance" doubled, but I suspect
that you simply didn't measure it carefully (if at all) and what you
report is just wishful thinking.

And like I said if data is backed up properly why worry?
Click to expand...


I'm entirely with you regarding backup. That's a necessity whether or
not you use RAID0. However, there is always a risk of backups not
restoring properly, getting lost, etc. Having backups is great;
relying on them to always be there working properly when you need them
is not so great.

And restoring from a backup takes time, and there can be a cost
associated with that too.

There is a much higher risk of losing data to a Windows failure than a hard
drive failure.
Click to expand...


I don't agree, but it doesn't matter, because it's irrelevant. The
point is simply that RAID0 increases the risk. And since it increases
risk for little or no benefit, it's not worth taking the risk.


Yes a stripe setup does increase the risk but the trade off
in performance increase is most definitely worth it.
Click to expand...


Once again, I disagree. The performance increase is somewhere between
tiny and non-existent. That's why I took it off my computer here.


The only way I might
not do it is in a business environment.

Ramone
Click to expand...
 
I don't know why performance did not double for you or anyone else. Maybe
it's due to hardware issues. But I can tell you for a fact that my stripe
setup on two different machines did factually double. I'm not trying to be
difficult, I'm just giving my opinion based on my experience. Maybe you
didnot use a hardware based raid?

Ramone


Ken Blake said:
Why did my hard disk performance double? Sorry Ken but you are wrong on
the
performance issue.
Click to expand...


That's your opinion. I disagree. I've tried RAID0 here and I saw no
discernable performance improvement at all. I know many others who
report the same thing.

I don't know why your "hard disk performance" doubled, but I suspect
that you simply didn't measure it carefully (if at all) and what you
report is just wishful thinking.

And like I said if data is backed up properly why worry?
Click to expand...


I'm entirely with you regarding backup. That's a necessity whether or
not you use RAID0. However, there is always a risk of backups not
restoring properly, getting lost, etc. Having backups is great;
relying on them to always be there working properly when you need them
is not so great.

And restoring from a backup takes time, and there can be a cost
associated with that too.

There is a much higher risk of losing data to a Windows failure than a
hard
drive failure.
Click to expand...


I don't agree, but it doesn't matter, because it's irrelevant. The
point is simply that RAID0 increases the risk. And since it increases
risk for little or no benefit, it's not worth taking the risk.


Yes a stripe setup does increase the risk but the trade off
in performance increase is most definitely worth it.
Click to expand...


Once again, I disagree. The performance increase is somewhere between
tiny and non-existent. That's why I took it off my computer here.
Click to expand...
 
Ramone said:
I don't know why performance did not double for you or anyone else. Maybe
it's due to hardware issues. But I can tell you for a fact that my stripe
setup on two different machines did factually double. I'm not trying to be
difficult, I'm just giving my opinion based on my experience. Maybe you
didnot use a hardware based raid?
Click to expand...

how did you measure it - using what tool?
 
I used 3 different benchmarks, both before and after setting up the raid 0.
HD Tune, HD Sentinel, and PCPitstop online test. On all 3 I went from 55-65
mb/sec transfer rate to 105-125 mb/sec transfer rate.

Ramone
 
Ramone said:
I used 3 different benchmarks, both before and after setting up the raid 0.
HD Tune, HD Sentinel, and PCPitstop online test. On all 3 I went from 55-65
mb/sec transfer rate to 105-125 mb/sec transfer rate.

Ramone
Click to expand...

So moral of the story is with SATA, hardware RAID 0 doubles performance (as
you shown), software RAID 0 but doesn't offer very much except for a lot of
potential risk (as Ken explained)!
 
Spin said:
So moral of the story is with SATA, hardware RAID 0 doubles performance
(as you shown),
Click to expand...

That is a very deceptive statement. Equating burst speed increases with
actual performance increases is misleading, that is just not an accurate
measure of performance! Most RAID-0 performance increases can usually
be measured in the range of less that 5%.

John
 
John said:
That is a very deceptive statement. Equating burst speed increases with
actual performance increases is misleading, that is just not an accurate
measure of performance! Most RAID-0 performance increases can usually
be measured in the range of less that 5%.

John
Click to expand...

Actually the Burst rate increase would not be much better, it would be
the sustained reads and writes that benefit from having the RAID 0. If
you are doing say video editing then yes a gain would be seen. But
little files that don't exceed the the onboard cache would maybe even
drop slightly from overhead on the two drives.
http://www.anandtech.com/storage/showdoc.aspx?i=2969&p=4
 
Back
Top